Blue copper sulfate pentahydrate (CuSO4.5H2O) crystals were heated to give the white monohydrate. What percentage of water was lost? (molar mass of CuSO4.5H2O is 250.5 g/mol)
Ok now you need to find the molar mass of the hydrate.
Then you divide the hydrate by the molar mass which is 250.5g/mol
%H2O = [(5*molar mass H2O/molar mass CuSO4.5H2O)]*100 = ?
To find the percentage of water lost, we need to determine the amount of water lost and then calculate it as a percentage of the initial amount.
First, let's break down the initial compound CuSO4.5H2O to understand its composition.
CuSO4.5H2O represents one molecule of copper sulfate combined with five water molecules. The molar mass of CuSO4.5H2O is given as 250.5 g/mol, which includes all of the atoms present in the compound.
Next, we need to calculate the molar mass of the water (H2O) molecule. The molar mass of water is calculated by adding the molar mass of two hydrogen atoms (2 * 1.008 g/mol) and one oxygen atom (1 * 16.00 g/mol), which gives us a total of 18.02 g/mol.
Since there are five water molecules in the compound CuSO4.5H2O, the total mass of water in one mole of the compound is 18.02 g/mol * 5 = 90.1 g/mol.
Now, let's calculate the percentage of water lost. We are given that the blue crystals of CuSO4.5H2O were heated to give the white monohydrate, which means that they lost some water. The difference between the initial and final compounds is that the initial compound had 5 water molecules, while the final compound has only one. Therefore, four water molecules have been lost.
The molecular weight of water is 18.02 g/mol, and since four water molecules have been lost, the mass of water lost is 18.02 g/mol * 4 = 72.08 g/mol.
To find the percentage of water lost, we divide the mass of water lost by the initial mass of CuSO4.5H2O and multiply by 100:
Percentage of water lost = (mass of water lost / initial mass of CuSO4.5H2O) * 100
Substituting the values, we get:
Percentage of water lost = (72.08 g/mol / 250.5 g/mol) * 100
Calculating this expression gives us:
Percentage of water lost ≈ 28.8%
Therefore, approximately 28.8% of water was lost during the heating process.